4-7 August 2020
Asia/Tokyo timezone

Long-distance contribution to neutrinoless double beta decays in pion sector

5 Aug 2020, 14:20


Weak Decays and Matrix Elements Weak Decays and Matrix Elements


Xin-yu Tuo (*) (Peking university)


Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then π−π− → ee and π− → π+ee (or equivalently π−e+ → π+e−) are the two simplest processes accessible via first-principle lattice QCD calculations. In this work, we calculate the long-distance contributions to the π
− → π+ee transition amplitude using four ensembles at the physical pion mass with various volumes and lattice spacings. We adopt the infinite-volume reconstruction method to control the finite-volume effects arising from the (almost) massless neutrino. Providing the lattice QCD inputs for chiral perturbation theory, we obtain the low energy constant gππv(mρ) =−10.89(28)stat(74)sys, which is close to gππv(mρ) = −11.96(31)stat determined from the crossed channel π−π− → ee decay.

Primary author

Xin-yu Tuo (*) (Peking university)


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